Ross,
I hope yours comes 'real soon'!
Talking about the valve gear...
Some testing was called for, so I found a suitable plug to connect the loco's 'lights' socket to my RC battery car.
She certainly runs smoothly, with sych'd chuff.
However, after the third violent derailment, I guessed there was some problem.
Each time I had only seen the other side of the loco, but the third time I looked at this side to find that the valve gear was hanging loose!
The hex head bolt that holds it to the centre driver was missing.
Was it missing originally, or had it fallen off?
I walked back round the track hoping to find it.
Amazingly, about 1/3rd of the way round there it was, conveniently lying on a darker flat bit by the track.
It, and its 5 brothers are now done up firmly.
Testing continues without more drama, so far.